The couple tied the knot before a selection of friends and family, including Bono and the Edge, in a traditional church in Deia, a picturesque village in Majorca, in 2002.
Caroline and Frank have three children, Jake (17), Georgina (16) and Rihann (13) and according to a close friend, will not be speaking publicly about the split.
Caroline has made one public announcement about the marriage break up on her Instagram page.
And in a clear sign that she plans to keep things amicable, in the message she wrote about the importance of maintaining a healthy relationship with her partner.
She posted a picture of the book, 'Conscious Uncoupling, 5 Steps To Living Happily Even After'.
Underneath the picture she wrote: "This book has been around a long time and I'm certainly not the first or will be the last to mention it.
"But I only started to really understand and like the term conscious uncoupling when going through my own separation some months ago after many, many years of marriage.
"Consciously endeavouring to maintain a good, loving and respectful relationship with my ex has been enormously beneficial to us both and especially to our children.
"I am also so aware and understand that this may not always be possible for many couples due to pain, fear, anger disputes and loneliness.
"These transitions are never easy for anyone and we cope and do our best at the time.
"I would recommend this inspirational and supportive book to anyone going through the difficult transition of separation or divorce."
Among those who offered her messages of support were singer Pearl Lowe and her sister Sharon, who said: "Love you sister."
Caroline is the latest member of the Corr family to suffer a marriage break up. Just a year ago, Sharon announced that she was splitting from her Belfast-born barrister husband Gavin Bonner.
Her guitarist brother Jim has a son Brandon (13) from his relationship with former Miss Ireland Gayle Williamson.
After bursting onto the scene in the mid-90s, The Corrs would go on to enjoy huge success, selling over 40 million albums worldwide.
The Co. Louth band had multiple hits in Ireland, the UK and the US most notably Runaway, Breathless and Dreams.
The quartet went on an extended hiatus in 2006 but returned in 2015. Their most recent album, Jupiter Calling, was released in 2017.
A talented musician in her own right, drummer Caroline is known affectionately by fans as the "Chick with Stick".
As well as drumming, she also plays the bodhrán, cajón, percussions and the piano.
The term 'Conscious Uncoupling' is famously associated with Chris Martin and Gwyneth Paltrow's marriage break-up.
The pair coined the phrase in a joint social media post back in 2014.
It was a term a therapist had used to get them on the same page about exiting their marriage but still co-parenting their kids.
The phrase certainly seems relevant for Caroline and Frank, who maintain a strong relationship despite separating.
"It is never easy for any couple to split up after 18 years of marriage but they are dealing with it the best way they can," a source told the Sunday World.
"Yes, Caroline is in a successful band and she is famous, but she has never courted the limelight.
"She wasn't the sort of person who showed up on red carpets or glitzy parties and she would like to keep her personal life equally as private.
"The post should really answer any questions that people out there have; anything else is private and she hopes that her family will be afforded the respect to do that behind closed doors.
"For now, both Sharon and Frank want to be the very best they can to make sure that everything is done for the good of their three children.
"I suppose, for this reason, the term 'conscious uncoupling', is particularly relevant as they have both maintained a strong, amicable relationship which allows them to co-parent their children."
Caroline and Frank still reside in Majorca, where they spend a lot of time together with the family.
And fans of the singer's Instagram page will know too things about her life; she loves cycling and her Cockapoo dog Jessie.
A representative for Caroline Corr declined to comment when contacted by the Sunday World.